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Anatomy & Physiology: Integumentary System and Hair

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  • Four main types of cells in the epidermis


    1. Keratinocytes
    2. Melanocytes
    3. Dendritic (Langerhans) Cells
    4. Tactile (Merkel) Epithelial Cells

  • Cells in the Stratum Basale (three)


    Basal Cells, Melanocytes, Tactile (Merkel) epithelial cells

  • Function of basal cells

    Continuously divide and replace cells, pushing them into the next epidermal layer.

  • Function of Tactile (Merkel) Epithelial Cells

    Specialized epithelial cells that work with nerves to detect touch.

  • Function of Melanocytes

    Produce melanin, a pigment that protects skin from UV damage.

  • Cells in the Stratum Spinosum (two)


    Keratinocytes and Dendritic (Langerhans) cells

  • Which epidermal layer is only in thick skin?

    Stratum Lucidum is present only in thick skin, not thin skin.

  • Function of Keratinocytes

    Responsible for keratin production in the epidermis.

  • Function of Dendritic (Langerhans) Cells

    Help initiate immune responses in the skin.

  • Which layer forms epidermal ridges and what is its function?


    Stratum Basale forms ridges that create fingerprints, increase surface area, and strengthen epidermis-dermis bond.

  • Deepest layer of the epidermis and its connection

    Stratum Basale is deepest and connects to the basement membrane via hemidesmosomes.

  • Cells in the Stratum Granulosum

    Cells have stopped dividing and produce large amounts of keratin.

  • Cells in the Stratum Lucidum

    Flattened, densely packed cells filled with keratin.

  • Cells in the Stratum Corneum

    15-30 layers of flattened, dead, keratinized epithelial cells connected by desmosomes.

  • Orange-yellow pigment in epidermal cells

    Carotene

  • What does carotene convert into and its purpose?

    Converted into Vitamin A, needed for epithelial maintenance and photoreceptor pigment synthesis in the eye.

  • Pigment made by melanocytes

    Melanin

  • What is a melanosome?

    A vesicle that stores melanin and colors the epidermis.

  • Does melanocyte activity increase or decrease with sun exposure?

    Increases with sun exposure.

  • Two major layers of the dermis

    Papillary layer and Reticular layer

  • Features of the papillary layer

    Contains dermal papillae, areolar connective tissue, capillaries, lymphatic vessels, and sensory neurons supplying the epidermis.

  • Features of the reticular layer

    Contains dense irregular connective tissue (net-like collagen and elastic protein fibers), sweat & oil glands, hair roots, and pressure receptors.

  • Layer deep to the dermis

    Subcutaneous layer (not technically part of the integument).

  • Function of the subcutaneous layer

    Stabilizes skin position relative to underlying tissue and allows independent movement.

  • Composition of the subcutaneous layer

    Areolar connective tissue with many fat cells.

  • Structure made of connective tissue containing capillaries and nerves in hair

    Hair papilla

  • Structure formed by repeated divisions of epithelial stem cells in hair

    Hair matrix, located just above the hair papilla.

  • Structure anchoring hair into the skin

    Hair root

  • Hair shaft definition

    The visible portion of hair above the skin surface.

  • Muscle that pulls hair follicle to make hair stand up

    Arrector pili muscle, made of smooth muscle.

  • Layers of the hair shaft and their keratin types

    Cuticle (surface, hard keratin), Cortex (middle, hard keratin), Medulla (core, soft keratin).

  • Two major exocrine glands of the integumentary system

    Sebaceous (oil) glands and Sudoriferous (sweat) glands

  • Types, functions, and locations of sweat glands

    Apocrine: secrete into hair follicles (Merocrine secretion); located in armpits, nipples, pubic region. Eccrine: secrete directly onto skin surface; widely distributed; function in evaporative cooling.

  • Five structures of nails

    Nail body, nail bed, nail root, cuticle, lunula